docs: add a more precise example

Previous example used manual integer value assignment in class based declaration but in functional syntax has been used auto value assignment what could be confusing for the new users. Additionally documentation doesn't show how to declare new enum via functional syntax with usage of the manual value assignment.

Author: Ret2Me

Doc/library/enum.rst

@@ -35,16 +35,17 @@ An enumeration:
 Enumerations are created either by using :keyword:`class` syntax, or by
 using function-call syntax::
 
-   >>> from enum import Enum
-
-   >>> # class syntax
-   >>> class Color(Enum):
-   ...     RED = 1
-   ...     GREEN = 2
-   ...     BLUE = 3
-
-   >>> # functional syntax
-   >>> Color = Enum('Color', ['RED', 'GREEN', 'BLUE'])
+   from enum import Enum
+
+   
+   class Color(Enum):
+       RED = '#FF0000'
+       GREEN = 65280
+       BLUE = '#0000FF'
+   
+   
+   # functional syntax
+   Color = Enum('Color', [('RED', '#FF0000'), ('GREEN', 65280), ('BLUE', '#0000FF')])
 
 Even though we can use :keyword:`class` syntax to create Enums, Enums
 are not normal Python classes.  See